Field of the Invention
The present disclosure generally relates to information processing and, more particularly, to an information processing apparatus, method, and storage medium configured to perform a three-dimensional measurement.
Description of the Related Art
A three-dimensional measurement technology using an image obtained by picking up a measurement target can be utilized for various purposes such as three-dimensional model generation from a real object and position and orientation measurement of an object. According to a stereo method corresponding to one of representative methods for the three-dimensional measurement technology using the images, the three-dimensional measurement is performed in accordance with a principle of triangulation based on images picked up by two cameras (stereo cameras) where relative position and orientation are known in advance. In addition, to increase the reliability of the three-dimensional measurement, a method of replacing one camera of the stereo cameras by an illuminating apparatus such as a projector that projects a pattern for the three-dimensional measurement onto a measurement target object is widely employed.
However, since a lens of the camera or the projector expands or contracts in accordance with a temperature, even when no physical position change between the camera and the measurement target object occurs, a shift of a position of a point on the measurement target object on an image sensor of the camera may be caused by a temperature change. Similarly, a shift of a position in a three-dimensional space of the pattern projected by the projector may also be caused by the temperature change.
The temperature of the lens changes by an outside air temperature or an internal temperature of the device such as the camera or the projector, and the lens expands or contracts. To perform the three-dimensional measurement at a high accuracy despite the presence of the temperature change of the lens, the shift caused by the expansion or contraction of the lens derived from the temperature change needs to be corrected.
Japanese Patent Laid-Open No. 2002-135765 discloses a method of performing a calibration of camera parameters under a plurality of temperatures in advance and switching the camera parameters in accordance with a measured value of a temperature sensor attached in the vicinity of the camera.
Japanese Patent Laid-Open No. 2002-135765 discloses a method of performing a calibration under a plurality of discrete temperatures. However, since only the calibration under the discrete and limited temperatures is performed according to the technology disclosed in Japanese Patent Laid-Open No. 2002-135765, it is difficult to perform an appropriate calibration in accordance with various temperature changes.